This invention relates to the preparation of N-alkylated compounds by reaction of an organic diacid, diester, anhydride or a lactone with ammonia and an alcohol. More particularly, the invention relates to the one-step preparation of a cyclic N-alkylated compound, such as a N-alkylsuccinimide, from an organic diacid, diester, anhydride or lactone by reaction with ammonia and a C.sub.1 to C.sub.8 alkanol either added or formed in situ. The ammonolysis-alkylation may be thermal or catalyzed. In another aspect of the invention a cyclic N-alkylated compound is formed in the presence of a reducing agent such that reduction of the process feed is accomplished together with the ammonolysis-alkylation reaction.
Previous syntheses making the N-alkylated derivatives from such compounds as a dialkyl succinate, succinic acid, succinic anhydride or 4-butyrolactone were carried out stepwise by first making a metal salt of the corresponding imide and reacting the latter with an alkyl halide or directly employing the reaction of a primary amine with the oxygen-containing starting material. These techniques are either multistep and expensive or simply expensive because of the price of primary amines. In a search for a low-cost, simple technique for carrying out these and similar reactions, it has been found that ammonolysis-alkylation can be accomplished in a single step in a thermal or catalyzed reaction employing ammonia and an alkanol, the alkanol either added or generated by the reaction in situ. The new reaction is capable of high conversions and high selectivities to the desired N-alkylated products, a finding of major commercial significance.
In the past, N-alkylated compounds have been prepared from dialkylsuccinates by thermal reaction with a primary amine. See U.S. Pat. No. 2,643,257. Of interest also is a two-step process for their preparation. A compound containing an imide nitrogen is first reacted to form an alkali metal salt, for example, potassium phthalimide, which is then reacted with an alkyl halide. See, for example, Gibson, M. and Bradshaw, R., Angew. Chem. Int. Ed. 7,919 (1963). Related to the present invention is (1) imide and amide alkylation with alcohols, see O. Mitsunobu et al. JACS 94,679 (1972), E. White et al., JACS 87,5261 (1965) and V. Evgrasin, et al., Kinet. Katal, 14,440 (1973) and (2) the reaction of maleic anhydride with a primary amine. See, for example, U.S. Pat. No. 2,262,262 and British Pat. No. 1,123,515.